#include <REGX52.H>
#include "delay.h"
unsigned char keynumer;
unsigned char key(){
	unsigned char keynumer=0;
	if(P3_1==0){Delay(20);while(P3_1==0);Delay(20);keynumer=1;}
	if(P3_0==0){Delay(20);while(P3_0==0);Delay(20);keynumer=2;}
	if(P3_2==0){Delay(20);while(P3_2==0);Delay(20);keynumer=3;}
	if(P3_3==0){Delay(20);while(P3_3==0);Delay(20);keynumer=4;}
	return keynumer;
}